1. Field of the Invention
The present invention relates to a memory card in which a nonvolatile semiconductor memory is mounted, and in particular, to a memory card in which a nonvolatile semiconductor memory having a predetermined erase block size is mounted, a semiconductor device mounted in the memory card, and a method of controlling a semiconductor memory.
2. Description of the Related Art
Some memory cards comprise a controller that converts addresses used by a host apparatus into addresses on an actual address. In such a memory card, the controller creates an address conversion table on a volatile memory such as a RAM on the basis of management information stored in a predetermined area of a nonvolatile memory such as a NAND flash memory. When the nonvolatile memory is accessed in response to an access request from the host apparatus, the controller executes an address converting process using the address conversion table.
Jpn. Pat. Appln. KOKAI Publication No. 2000-284996 discloses a memory managing apparatus comprising a detection table in which assigned and unassigned blocks are identified for each of a plurality of zones of a predetermined size each into which a memory space on a memory device is divided, and a management table generated by associating physical addresses with logical addresses in individual blocks in a selected zone.
If a memory card in which a memory having a specification different from that of a memory assumed by the host apparatus is configured to be applicable to the host apparatus, address converting processes are complicated. Further, the amount of information in the address conversion table correspondingly increases. In such a case, a RAM or the like in which the address conversion table is stored must have a large capacity.
However, if a large RAM is mounted in the memory card, a mounting area and costs increase. Further, a relatively long time is required to expand the address conversion table, having a large amount of information, onto the RAM on the basis of the management information on the nonvolatile memory. Accordingly, temporal restrictions described in the specification of the memory card may fail to be met.
Furthermore, the technique in the above document requires another table (detection table) in order to create the management table for address conversions. Thus, disadvantageously, the volatile memory such as a RAM must have an increased capacity.
It is thus desired to allow processing to be more efficiently executed while reducing the amount of information stored in the volatile memory such as a RAM.